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Yuasa L36efb - Voltage dropping ?


trialsrider

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Just fitted a new 100ah yuasa L36efb. I've done about 4 cycles so far. Set up is a Sargent ec160 but I'm charging via a Ctek charger. I have a 100w solar panel too. Charged battery all day sat and switched off sun after charger said it was charged. After an hour's rest with nothing on except the panel led on Sargent the voltage was 12.9. this morning I checked again and voltage was 12.7. This was at 5am before the solar begins any charge. Nothing had been used in the van and nothing else is on except the Sargent panel. Is this voltage drop normal in such a short time.

 

I am worried the new battery is not 100%. When I took delivery of it from alpha batteries only one plug was in situ and I was worried in case it may have leaked. Should the voltage be dropping like this ? Last week it dropped to 12.5 after being stood for 5 days with no use.

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A battery does not arrive fully charged, typically it will have only 85% charge, that is why manufacturers state that a habitation battery should be charged for 24 hours before use.

Even when fully charged, it can take a battery many cycles to reach full capacity. See in the graph below how the Hankook battery arrives with 85% capacity and takes nearly 60 cycles to reach full capacity.

 

 

A Yuasa batteries resting voltage, it's State Of Charge (SOC) is typically 12.8v tabled at 20 - 25 degrees C when open circuit, i.e zero load.

Temperatures of close to zero will affect the battery voltage and capacity significantly, hence car Starter batteries turning the engine over more slowly in sub zero temperatures making some cars harder to start in winter..

 

If you checked the battery voltage early this morning before the sun came up, then 12.7v at what was only 2 degrees C here, suggests a reading of 12.7v is good. Bear in mind that even just turning on the Power distribution/controller may place some load on a battery, some as much as 0.3amps

 

Remember as well that Solar controllers draw back overnight some of the power they put in during the day. A mains charger will also be drawing small current and placing a load on the batteries. This will occur for these devices irrespective of the best blocking diodes installed inside them and a Leisure battery charger usually has much better blocking diodes than a CTEK which is usually designed to be disconnected when the battery is 'full', not left connected like a motorhome specific charger.

So while you think there was no load on the batteries, there would have been something taking small current.

.

If the EC160 has been installed using a VSR, then that will be continually drawing small amounts of current 'looking' for the Starter battery voltage to rise. The 2 part VSR we advocate doesn't draw power when idle.

 

 

The Yuasa L36-EFB does not have the higher SOC that a Varta LFD does.

While a Varta will deliver close on 13.0v (see second photo of a Varta LFD90 after resting a while, zero load and about 20 degrees) the Yuasa won't but the Yuasa does have a slightly longer cycle life and 100Ah capacity.

 

 

.

 

 

368591167_Hankookdc31chargedischargecapacitygraphsmall.jpg.73bfee9601fdddd0b0b5fdbb8b33686e.jpg

1069447128_VartaLFD90fullychargedandrestedsmall.jpg.a5abba6a02cf24dad48d3cd48868de8b.jpg

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aandncaravan - 2019-02-19 10:48 AM

 

A battery does not arrive fully charged, typically it will have only 85% charge, that is why manufacturers state that a habitation battery should be charged for 24 hours before use.

Even when fully charged, it can take a battery many cycles to reach full capacity. See in the graph below how the Hankook battery arrives with 85% capacity and takes nearly 60 cycles to reach full capacity.

 

 

A Yuasa batteries resting voltage, it's State Of Charge (SOC) is typically 12.8v tabled at 20 - 25 degrees C when open circuit, i.e zero load.

Temperatures of close to zero will affect the battery voltage and capacity significantly, hence car Starter batteries turning the engine over more slowly in sub zero temperatures making some cars harder to start in winter..

 

If you checked the battery voltage early this morning before the sun came up, then 12.7v at what was only 2 degrees C here, suggests a reading of 12.7v is good. Bear in mind that even just turning on the Power distribution/controller may place some load on a battery, some as much as 0.3amps

 

Remember as well that Solar controllers draw back overnight some of the power they put in during the day. A mains charger will also be drawing small current and placing a load on the batteries. This will occur for these devices irrespective of the best blocking diodes installed inside them and a Leisure battery charger usually has much better blocking diodes than a CTEK which is usually designed to be disconnected when the battery is 'full', not left connected like a motorhome specific charger.

So while you think there was no load on the batteries, there would have been something taking small current.

.

If the EC160 has been installed using a VSR, then that will be continually drawing small amounts of current 'looking' for the Starter battery voltage to rise. The 2 part VSR we advocate doesn't draw power when idle.

 

 

The Yuasa L36-EFB does not have the higher SOC that a Varta LFD does.

While a Varta will deliver close on 13.0v (see second photo of a Varta LFD90 after resting a while, zero load and about 20 degrees) the Yuasa won't but the Yuasa does have a slightly longer cycle life and 100Ah capacity.

 

 

.

 

 

 

Thanks Allen for the swift and illustrated answer. Looks like all is well and I just need to charge it s few times.

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